An artist's illustration of Kepler-64b or PH1, a planet discovered by volunteers from the Planet Hunters citizen science project. PH1, shown in the foreground, is the first reported case of a planet orbiting a double-star that, in turn, is orbited by a second distant pair of stars. The phenomenon is called a circumbinary planet in a four-star system.

A bit larger than Neptune and thought to be a gas giant, PH1 orbits its host stars every 137 days. Beyond the planet's orbit approximately 900 times the distance between the sun and Earth, a second pair of stars orbits the planetary system.